Germs and a lesson learned

Tonight we met Steve, Sherry and Jennifer for dinner at Chipotle. During dinner, Winston pulled out Dave's old keychain, which included a Swiss Army knife. We told Winston that was not a toy, he needed to put it in his pocket, and we'd talk about it when we got home.
Well, on the way home, Winston opened the knife. We couldn't see in the dark back seat, but about half way home he told us that he'd cut his finger. Then he started crying because he could feel the blood, and I'm sure it hurt, too.
When we got home, we got him and his very minor cut all cleaned up. It was bloody enough to cause him enough alarm so that he hopefully won't repeat the same mistake, but thankfully it was relatively small.
As I put him to bed tonight, he said he didn't want to tell anyone what had happened. I suggested that if anyone asks, he could just say that he cut his finger. Again, he said he didn't want to tell anyone. Then his eyes welled up with tears and said he really didn't want to tell Sadie (Lake). I asked and asked and asked why, just trying to understand why he didn't want to tell her and why this made him so sad. Finally, he said he didn't want to tell her because then she might think he has germs and wouldn't want to be by him anymore.
Oh my sweet, dear boy!!!